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G. w. BALD HOT AIR ENG No.- 48,639. PatentedJ'uly 11, 18 65.

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' 3 SheetsSheet 2. G. W. BALDWIN. HOT AIR ENGINE.

-No. 48,639. Patented July 11, 1865.

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IIIIIIII NE 7 Patented July 11 1865;

' useful Improvements in a &c. Fig. 3

UNITED STATES FFICE.

PATENT c-YRUs w. BALDWIBT, or

i M PROV E-M'Ei'i'il N BOSTON, MASSACHUSETTS.

HOT-AIR enemas;

Specification forming part of Letters Patent No. 48,639, dated July 11, 1865.

To all whom't't may concern:

Be it known that I, CYnUs W. BALDW1N, 0f Boston, in the cgunty of Suffolk and State of Massachusetts, have invented certain new and Hot-Air Engines; and I do hereby declare that the following, taken in connection with the drawings which accompany and form part of this specification, is a description of my invention suficient to enable those skilled inthe art to practice it.

This invention relates to details and arrangements of parts by which the action of hot-air engines is improved and their durability increased. V r

0f the drawings, which embody and illustrate this invention, Figure 1 is a side elem tion of those main parts of an engine within which my invention is incor 'orated. Fig.2 is a vertical sectional view t en in the irregular line a b, span in Fig. 3, the section showing the piston-packin g, the exhaust-valve and passage, the air-pump and its delivery-passage, is a plan and a partial horizontal section taken in the line on, seen in Figs. 2 mild, said figure-showing particularly the system of air-passages. Fig. .4 is a plan with the working-cylinder and its piston removed. Fig. 5 is a section taken horizontally through the bed-plate, .which is'shoygn in inverted position, the section discovering the cold-air passage from the pump and the ex"- haust-passa'gey from theengine-cylinder. Fig. 6. is a vertical section on the line a d, seen in Fig. 3, showing particularly, in connection with Fig. 7, the construction of the top of 4 the firebox.- Fig. 7 is a. horizontal section taken on the line a f seen in Fig. '6. Figs. Sand 9 are perspective views showing the leather pistonpacking. V s

Practical experience has shown me that for heating large quantities of air, such as are re. quired for the supply of hot-air engines, the purpose is, better accomplished in small fur, naces than it is in one large one of the same on his capacity with two or more small ones; The

reason in this, I apprehend, is that air being} va. poor conductor of heat prevents the heating i of a large body uniformly throughout, while in a number of smaller furnaces all portions of the air therein wouldbe nearer the fuel or the heated furnace-boundary than some of thenrwonld be y it the body-of air were not subdivided, and concylinder being supplied on one side only of its piston from said two or more fire-boxes.

In the drawings, 9 '9 shows the non-conducting lining of the furnaces, two being shown. These1furnaces deliver their heated air into apipe, h, which is common to both furnaces, and which supplies one engine-cylinder. As this pipe affords means for freecommunication between both furnaces it will be evmgptthanthe stop-,valves, so arranged that one -furnace could be shut 011' from the other or others while replenishing the fact in the furnace thus detached, or while it is undergoing repairs, the engine in the meantime being supplied from thefurnace or furnaces not shut off.

To cut 0d the blaze proceeding from the fuel from the engine-supply vaive,which blaze,'with some kinds of ,fuel, is very long, and. also to intercept ashes and other solid matters, so as to prevent them from being carried to the valves and cylinder,1 makes. tortuous passage around the top of the furnace for the volatile products consists another portion of my invention.

Above the lining g of the furnace, and resting' thereupon in the outer-casing, i, is a hollow head, j, (see Figs. 6 and 7,) in which is a passage into which the current from the furnace enters through the opening 70, and moving through the passage in j in the direction shown by the arrows, (see Fig. 7,) discharges through the opening i into pipe 7:...

- A coiled iron .diaphragm from I might be employed in lieu of the head j.

Still further to keep ashes and solid matter from being carried into the engine-cylinder andthe valve-seats, I introduce all of the air, both that which is heated and expanded merely and that which supports combustion, wholly above the fuel. By so doing} avoid the upof heated air to the requirements thereof, each.

pressure obtained in due will also be obtained in the other. In said pipe might be placedof combustion and the-heated air, and in this psimpe, protec ed bya plate or t e direct action of the heat,

ing about the valve-chest is marked '8.

ward blast of air through the fuel, which necessarily carries with it a considerable amount of duced, provided it. does not pass among the fuel in entering the furnace.

In Fig. 3 it will be seen that the air-supply -,pa-ssages for the furnace are marked m,'and

they debouch into the openings n in the ver i tical walls of the furnaces, through which fuel may be introduced to rest upon't'he grate 0. Besides the opening it into the furnace, there is another, (shown at 1),) through which fuel can be supplied, but these openings, as well as that seen at q, through which the-ashes are removed, must be closed to the atmosphere when the engine is set in operation.

To utilize the heat radiating from the top of the furnace it may be provided with a hol- -low cap, r, designed to be kept supplied with water, so that the'escaping heat shall be utilized by vaporizing the water, which may be" employed as-is needed, either by introduction into the furnace to aid and support combusltjlon, or otherwise, as may be deemed desira- Much trouble has hitherto been caused by oxidation and wear of valves and valve-seats, consequentupon excessive heatin g of the same. To avoid the troubles consequent upon .heating ofsaid parts I'incase them and thepipe leading thereunto from the furnace, and admit into the space surrounding the valve-chest and supply-pipe the cold air which is suppliedby the force-pump, so that said air as it moves toward and into' the furnaces shall surround the valveehest and supply-pipe and shall absorb the heat radiated therefrom,thus keeping down the .temperature which they would otherwise have, the heat so abstracted not being lost, as it passes with the air into the furnaces. It is in thus incasing the "alve chest and causing the air from the force-pumpto surround said chest on its' passage to the furnace that another po'rtion' of my invention consists.

The passage from the force-pump to thecas- See Figs. 2, 3, and 5.) The valve-chest is mark ed t, and the casing surrounding it is marked w.

The pistons of hot-air engines, being guided less perfectly than those of steam-engines, on account of using yielding packings of leather instead of metallic packings, are more apt to be deflected and made to wear sidewise from slight causes than are metal-packed pistons. Heretofore it has beenconsidered sutficient to introduce theimpelhng medium'anywhere into the cylinder below the bottom of the enginepiston, and hence the port has been made to open into the cylinder on the sidenearest'tlie source of supply.

One portion of this construction shows a manner ofsupplying the impelling medium so that it, will act squarely and centrally upon the piston and it consists in locating the-entrance-port directly under the center of the piston, by which location I find a material im provement in the working of the engine and a saving in the wear of the piston-packing. This port. is marked i and is seen in Figs. 2, 4, and 6.

The c \-linders of hot-air engines are made in;

two partsun upperone, whichisbored smooth for a packed piston to work in, and a lower one, which is left largerindiameter and into which the extension part of the piston descends. without touching: This lower cylinder has heretofore been formed of iron, and it has-been encompassed by an iron'ca sing, the space between the-two iron parts having been in some casesleftvacant, o'rrather filled with air as a non-conductbr of heat, and in other instances the space has been filled up-witlmuitable solid non-conductors, as tire-brick, for exam-pie.

This part of my invention consists indispensing with the use and-cost of the inner iron cylinder and in filling the space left between the casin g to and the piston, when at its lowest stroke, with soapstone, fire-brick, or other suit: able solid non-conductor, taking care that the interior diameter of the lower part of the cylinder is such as to give a clearance to that part of the piston which enters therein.

The outer casing of thelower part of the cylinder is marked w, and the filling which makes the lower cylinder is shown by ac. In this connection it may be remarked that the lower boundary of the cylinder may be. advantageouslyand cheaply made, including the port a, of masonry, resting on the iron bed-plate, thus rendering the use of-iron plates and a cellular structure unnecessary.

As the pistons of hot-air engines are packed with lcather, and as such packings require to be renewed'frequently, and as the pistons are of considerable size for the power obtained, as compared with steam-engine pistons, and as said leather packiugs have hitherto'been cut out of large disks of leather, involving considerable waste and cost, it is a desideratuin to obtain a leather packingwhich shall beof less cost, and this may be accomplished by taking a plain strip of leather, like a piece "of belting,

and of width sui'iic'ient to lap over-the -top of the piston and be secured thereupon under and by the follower, (see Fig. 2,) and also to make a right-angled turn and encompass the work lug-face of the piston, in the manner of the common cup leather packing. This strip, which in the plain form is shown by Fig. 8, is moistened and crimped or bent to a fiat ring of the right diameter, care being taken to have the ends meet with a good joint. In'this condition it is secured to the piston by thefollowe'r, and the projecting edge of the leather ring is then bent downward by forcing upon the piston from above and over the leather a suitable ring leather onbanu which is allowed to remain until the lries, when it will retainithe form given Instead of using the piston and follower to prepare the packing, a block and ring of the diameterof the piston and follower may he used.

I claim-- 1. In a hot-air engine, the arran ement, substantially as described, by which a single cylindelis supplied on one side only of its piston from two or more furnaces, which are separate from each other as to the means for the reception in each of fuel and air, but which discharge their gaseous products of combustion into said cylinder, as stated, through a commonvalve-chatnben- 2. Providing at the top of the fire-box of a hotair engine a-passage around the same for conductingthe'gaseous products of combustion to the cylinder, so asto out 01f therefrom and from the valve-chamber actual flame, and to cause deposit of solid matter, substantially as specified.

cylinder without any metallic inner boundary, vand of fire-brick or other suitable non-con:

ductor supported by a metallic easing, substantially as specified.

In witness whereof I have hereunto setmy hand this ldthda-y of -March, A. D1865.

CYRUS W. BALDWIN.

In presence of-- J. B. Caesar, W. B, GLEASON, 

